department confirmed the u.s. diplomatic mission in benghazi, libya, was under attack. searches for the british monitoring group called it a well-planned assault that occurred in two ways. the sources said the attack involved a group of about 20 militants and included heavy artillery, machine guns, and rocket-propelled grenades. by morning, it was confirmed that four american diplomats, including the u.s. ambassador to libya, christopher stevens, were killed in the attack. that makes stevens the first ambassador killed in the line of duty since 1988, when arnold raphael, the ambassador to pakistan, died alongside the president of pakistan in an unexplained plane crash. president obama addressed the nation from the white house rose garden this morning. about 50 u.s. marines were deployed to libya and two u.s. warships are headed towards the libyan coast. secretary of state hillary clinton addressed the sad irony of the attacks in the wake of the u.s. support of the libyan revolution. >> today many americans are asking, indeed, i asked myself, how could this happen? how could this happen